5-Aminolevulinic Acid Dehydratase Gene Dosage Affects Programmed Cell Death and Immunity

Abstract

Programmed cell death (PCD) is an important form to protect plants from pathogen attack. However, plants must precisely control the PCD process under microbe attacks to avoid detrimental effects. The complexity of how plants balance the defense activation and PCD requires further clarification. Lesion mimic mutants constitute an excellent material to study the crosstalk between them. Here, we identified a (cotton) lesion mimic mutant (), which exhibits necrotic leaf damage and enhanced disease resistance. Map-based cloning demonstrated that , encoding 5-aminolevulinic acid dehydratase and located on chromosome D5, was responsible for the phenotype. The mutant was resulted from a nonsense mutation within the coding region of It exhibited an overaccumulation of the 5-aminolevulinic acid, elevated levels of reactive oxygen species and salicylic acid, along with constitutive expression of pathogenesis-related genes and enhanced resistance to the infection. Interestingly, plays a dosage-dependent role in regulating PCD of cotton leaves and resistance to infection. This study provides a new strategy on the modulation of plant immunity, particularly in polyploidy plants.

Effects of δ‐aminolevulinic acid dehydratase silencing on the primary and secondary metabolisms of citrus

“…In agreement with our results, Chai et al. () reported an increase in the level of ROS and H 2 O 2 in Gossypium hirsutum (cotton) lesion mimic mutant ( Ghlmm ), which exhibited an accumulation of δ ‐ALA as a result of low activity of the ALAD enzyme. An increase in methanedicarboxylic aldehyde (MDA) level was also observed in mutant leaves, indicating peroxidation of unsaturated membrane lipids in cells.…”

“…An increase in methanedicarboxylic aldehyde (MDA) level was also observed in mutant leaves, indicating peroxidation of unsaturated membrane lipids in cells. Silencing of ALAD in G. hirsutum by the TRV‐based VIGS also resulted in the same phenotype observed in mutant plants and showed an accumulation of δ ‐ALA and H 2 O 2 (Chai et al., ). The mutant plant also accumulated SA and showed high expression levels of pathogenesis‐related genes (PR) and high resistance to Verticillium dahliae infection (Chai et al., ).…”

“…Silencing of ALAD in G. hirsutum by the TRV‐based VIGS also resulted in the same phenotype observed in mutant plants and showed an accumulation of δ ‐ALA and H 2 O 2 (Chai et al., ). The mutant plant also accumulated SA and showed high expression levels of pathogenesis‐related genes (PR) and high resistance to Verticillium dahliae infection (Chai et al., ). In addition, modulation of ALAD activity was found to control programmed cell death (PCD) and PR expression (Chai et al., ).…”

Melatonin enhances cotton immunity to Verticillium wilt via manipulating lignin and gossypol biosynthesis

“…To detect and quantify the biomass of V. dahliae in cotton seedlings, the first true leaf of cotton plants at 22 dpi was collected for DNA extraction. qPCR was used to quantify the relative amount of fungal DNA (Chai et al ., ).…”

Suppression of tryptophan synthase activates cotton immunity by triggering cell death via promoting SA synthesis

“…Many lesion‐mimic mutants have been reported, and about 40 associated genes have been isolated (Bruggeman et al ., ). Those genes fall into several functional groups, including ‘membrane‐associated protein’ (Büschges et al ., ), ‘ion channel’ (Balague, ), ‘zinc‐finger protein’ (Dietrich et al ., ), ‘porphyrin metabolism’ (Chai et al ., ), and ‘fatty acid metabolism’ (Sun et al ., ). In our study, we found a group of lesion‐mimic mutants that participate in tryptophan synthesis.…”